One Universe Apart
by withabluepen
Summary: In the midst of bitter defeat and bloody battlefields, Uchiha Sasuke makes a choice that will go against the laws of time and space- in exchange for his life. timetravel!au. no pairings. written with Lovingthefantasy!
1. part one

The battlefield was void of the cries of carnage, which felt unfamiliar to Sasuke's ears. It unsettled him to no end, the silence. He made note of the battered body of his rival lay motionless somewhere in the midst of corpses, his blond hair caressed by the breeze and his dull, azure eyes gazing blankly into the dark night. The silence held its breath, making Sasuke clench and unclench his hands anxiously.

It was almost as if he were wading through the ocean, for he had lost mostly, if not all, perception of being and distance. His universe seemed to be just him, the withered moon, and the destruction that encompassed him.

His heart seemed to weigh him down as he stood up, surveying the scene; these people weren't supposed to hold any meaning to him, yet he felt like the whole world had suddenly shattered into a million pieces.

Grief was a wicked, traitorous thing.

Sasuke examined his surroundings as the crimson moon hung overhead, almost like it was mocking him. From the corner of his eye, he spotted a silver-haired ninja bathed in blood, mask almost torn off. He seemed to be dead, like the countless others that surrounded him. Suddenly, his body twitched a little, something that Sasuke would've missed if it weren't for his unnaturally sharp perception, honed through countless life-risking situations. Without hesitation, he rushed over to the ninja's side, crouching down and placing two fingers on the ninja's wrist. A faint beating of the pulse could be felt.

His mentor slowly opened one eye, attempting to open his mouth to say something, only to come out in the form of a pained gasp. Sasuke could see that the man was bleeding in multiple places on his body, many of which were certainly fatal wounds.

"Don't speak," Sasuke murmured, gazing into his sensei's sole iris. The silver-haired jounin lifted his lips slightly, forming a small smile. Sasuke gulped; time seemed to drag on, letting the pain of the reality sink in.

"Quite a sorry state for the son of the White Fang of Konoha," he remarked softly after a moment of silence, earning another feeble grin from the man.

"N-Naruto never d-did give u-up on y-you," Kakashi forced out, each word heavy with agony. He winced as more blood spilled out from a chest wound, flowing onto the ground. Sasuke widened his eyes, his breath cut off short.

"That idiot only went and got himself killed," he muttered, "Reckless, as always."

The silver-haired man beamed proudly, the light slowly dying from his eyes. "You're a good kid," he whispered. Sasuke scoffed, turning his head away from the dying man. He stayed silent as the faint sounds of Kakashi's breathing slowed, before ceasing completely.

A figure suddenly materialized by Sasuke's side, making him move away quickly by the unexpected proximity. Uchiha Madara stood next to Sasuke, gazing into the distance.

"You vengeance has brought you here, young Uchiha," Madara's eyes bore into Sasuke's. "Have you found what you sought for?"

Sasuke's eyes hardened as images of the fading smile of a dying man flashed before his eyes.

"I'll give you a chance to change everything," he continued on quietly, "But there will be a cost."

Sharingan gazed into sharingan, both holding their ground as they tried to read each other. Sasuke could not see a shred of dishonesty in Madara's, while Madara was pleased to see signs of curiosity escaping the barrier that the young Uchiha had built around himself.

"Why would you give me a chance?" Sasuke replied, his voice slightly raspy. He gritted his teeth, feeling displeasure growing in his chest. "Do you pity me?"

"It is hard not to appear pitiful, with you in this state; you're not wrong, you do look no different from a dead man right now. But now that I think about it, what is the meaning of power when there is nothing to control, no soldiers to command?" Madara lamented as he gazed over the vast sea of corpses.

Sasuke bit down on his cheek and clenched his bloody hands, "Then why-"

"I expected that Kyuubi boy to stop me. I guess I overestimated his abilities, and now he is dead, even before I could harness his powers," he laughed, "In all honesty, it is quite a shame."

Sasuke felt something akin to rage bubbling in his stomach. He forced it down, knowing that it would do him no good, since he wasn't capable of killing the man next to him. "So you're giving me another chance to kill you?" Sasuke asked, clenching his jaw.

"Something like that."

The young Uchiha narrowed his eyes suspiciously at the man's elusive reply. "What's the cost?"

Madara smiled slyly, "Well I can't tell you; you're just going to have to find out for yourself."

Right, of course, Sasuke sneered at his elder. There's no way Madara would tell him. "Then if I take it…" He stared at the remains of his allies and enemies. The bloody moon hung high as the breeze lifted the damaged souls through the darkened skies. The mountain of bodies stacked up tall, for all were killed at the same place by the same man.

Madara had become god, his goal was complete. Sasuke had arrived late to the battle, and the ancient Uchiha had already killed off all the shinobi that he once knew. And the longer that Sasuke thought about it, the more he realized that he no longer had a reason to live. The bodies that lay on the field were of the people that he had grown up with, and somehow Sasuke still cared for them.

"So, young Uchiha, what will it be?"

"I'll take the chance," Sasuke sighed. Maybe he could fix everything that he screwed up in this lifetime. Maybe he could make it so that no one would have to die. But Sasuke was sure, this time, fate was going to change. Even if it costed him his life.

"Then come here, young one."

Sasuke hesitated, but slowly started toward Madara. He motioned for Sasuke to sit before sitting down in front of him, beginning his jutsu. They both closed their eyes as the Uchiha made many swift hand signs, causing the air around them to thicken with energy. Madara suddenly stopped, opening one eye.

"This will be a little painful, my descendent," he said, before slamming his hands into Sasuke's chest. The young Uchiha felt himself gasp as excruciating pain permeated throughout his entire body, starting from the bottom of his spine before entering his head. The searing pain made it feel as though Sasuke's skull was being shattered as he screamed out in agony, clutching his head tightly. Blood tears rained from his eyes; he felt as if his limbs were getting ripped apart from his body, one at a time. He couldn't help but open his eyes in terror and wildly rake his fingers through his hair in a desperate attempt to appease his suffering.

The last thing he saw was Madara grinning like a madman before darkness enveloped him completely.

* * *

For a split second, Sasuke couldn't feel anything - it was as if all his senses had been cut off. When he tried to breathe, there was nothing. Panic pulsed through his veins, making him feel vulnerable all over. Pain pounded in his head like a hammer. He tried to scream as his body became battered with agony, there was no sound that came out. He felt lost, which frightened him, as it meant that what his purpose of living was had slipped away from him.

And that could not be more scary to Sasuke than anything in the world. He wasn't one for recklessness, but when one had nothing left, they only had a choice of letting go or seeking something to change.

Sasuke was not one to give up; he knew of his stubbornness and let it become part of him, even though he would never admit it.

As soon as it had started, it was over. The pain suddenly vanished, leaving nothing but bliss to take its place. Relief coursed through him when he felt a heavy thump, his body making contact with a hard surface. He felt the air get knocked out of him, leaving him momentarily stunned.

Sasuke sat up groggily, his arms shaking slightly as he did so. His body felt sore and his head dizzy as he let his eyes adjust to the new brightness of the room. Slowly opening them, he was surprised to find that it was daytime, and possibly sometime during midday, considering the glaring sunlight that shone into the room. He looked around frantically, eyes widening and mind racing as the Uchiha analyzed his location.

The calm, milky walls, the bamboo sheet-covered floor, and the symbol of the Konoha military police force placed orderly around the room. He knew it all too well: Uchiha Sasuke was back home.

* * *

 **author notes:**

Many thanks to aria de capo for being our beta. /sends you lots of love/

 **lovingthefantasy:**

Hello~ I am working with withabluepen to write this fanfic. If you go on my fanfic account you're just going to see a really cheesy Percy Jackson fanfiction that I wrote in 2014. I hope you very much enjoy this Naruto fanfiction. Our updates are going to be very inconsistent…

Oh, and Happy New Year!

 **withabluepen:**

I know we're writing the generic timetravel!au for naruto, but we plan on making it a little different/putting our little twist on it to make it unique. Thanks for reading and please review if you have any suggestions or questions! Constructive criticism is appreciated.

Merry Christmas/Kwanzaa/New Year/holidays that I don't know of!


	2. part two

_Kai!,_ Sasuke commanded, testing the waters. To his disappointment, nothing happened, confirming that it wasn't a genjutsu. He frowned and pursed his lips. One question continued to nag him- why was he in the Uchiha compound?

As he stood up, he noticed that the furniture around him seemed to appear unnaturally tall. Taking tentative steps around the room, Sasuke inspected his surroundings more closely. It had been many years since the last time Sasuke set foot into his own bedroom.

Sunlight shone into his room, warm on his skin. Something seemed off- Sasuke thought it would be preposterous, but it was almost as if he wasn't in the body he was used to being in. He glanced down at his hand, his breath caught in his throat. Why did his hands look so _small_?

Sasuke slowly opened the front door of his home, confusion overwhelming his mind. Light poured through the exit as he stepped outside. He glanced into the distance at the Hokage mountain and froze. Unconsciously, he stepped out the door, staring at the monument. There were only four faces carved onto the mountain. Sasuke scrunched his eyebrows and frowned, his brain whirring as it processed his new surroundings. _Shouldn't there be five Hokages? What happened to Tsunade?_

Realization suddenly hit the Uchiha like a brick. _His theory was certainly far-fetched, but not impossible…_ He darted back inside into a bathroom and examined himself.

To his disbelief, what he found in the mirror was not the face of seventeen year old Uchiha Sasuke, but instead a face soaked in the waters of youth. The creases on his face- a result from constant stress- were no longer there. Sasuke touched his cheek softly, astonished by his new appearance. _So this was the opportunity that Madara had promised him…_ To confirm his suspicions one last time, he ran into the living room where a calendar hung from the wall. _At around this time, it seems that I would've already graduated the Academy? I'm not wearing the clothes that I regularly did when I was younger._ Instead, he had the standard uniform of a jounin, with a green vest, navy blue pants, and dark sandals.

When he turned to look at the back of his neck, the curse mark was no longer there.

 _I wonder if I'm still associated with Orochimaru in this world,_ Sasuke mused. He strolled around his old home, exploring his childhood and returning to the memories he thought he had lost long ago. Suddenly, the Uchiha stopped in his tracks and stared at a photo of his family. There were four members in the picture: his mother, father, him, and Itachi. His mother was smiling brightly in the picture, along with him. Itachi had his small trademark grin on, and his father was solemn as always.

A little part of his heart panged, remembering how that was what his happiness was like before everything started going haywire. _Did he even remember how to smile so widely anymore?_

But something about the photo seemed strange to him- almost... unnatural. Sasuke peered closer and froze. Itachi looked young, _too_ young. Traditionally, in family photos, the youngest stood in the front, between the mother and the father. From the way his family was positioned in the picture, his assumptions could possibly serve themselves to be true: Itachi was no longer his older brother.

Sasuke carefully examined the image of Itachi, still dumbfounded. His brother's face was certainly more youthful compared to him, but not by much. It took him by surprise, since he'd never imagine a time when he'd would be the older one of them two, and not _Itachi_.

Frankly, he never imagined that such a jutsu that could allow travel to the past could have ever existed, nevermind the older-brother business.

He snapped out of his thoughts as he heard the slight creaking of the front door swing open and close. Suddenly, Sasuke was at his feet and on guard, silent as a snake as he slithered next to the entrance of the room to peek at whom it was.

Quiet footsteps approached the corner of the hallway as the sound of a door being slammed closed resonated throughout the compound. Sasuke glanced out from the room, identifying the door that Itachi entered through. He slipped into the hallway, wondering about how he should act based on the situation at hand. The Uchiha came to a conclusion to check on his (now) younger brother.

Feet lightly stepping onto the wooden floorboards, Sasuke made his way to the entrance of Itachi's room and knocked gently on the door.

"Go away," a muted voice responded, but Sasuke entered anyways. For a split second, Sasuke blanched, unaccustomed to this form of his brother. _How many years has it been?_ Itachi turned his head and glared at him from where he sat, "I'm busy right now, Nii-san," he paused, before continuing, "Do you know where Mother and Father went?"

"They're out attending to some clan business and such," Sasuke responded smoothly, wondering if it would be an adequate lie since he didn't know where they were. Itachi was oddly still as he stared straight into Sasuke eyes, as if searching for something to refute him.

"What's wrong?" Sasuke asked cautiously as he returned the notion, both of them silent as mice. Suddenly, there was only a blur of black and the cold kiss of a metal kunai blossoming at the base of his neck. Murderous intent seeped out from behind him, making him stiffen slightly.

"Who are you?" Itachi demanded, the sharp tip of the weapon digging into Sasuke's skin. Sasuke held Itachi's wrist tightly, holding back the weapon from piercing his neck. He narrowed his eyes, unaccustomed to the measly amount of strength he could muster.

"Your brother?" Sasuke replied unintelligently. Itachi seemed to pause for a moment, as if pondering the offered concept. After a few seconds, he dropped his arm, releasing Sasuke from his hold.

"Please refrain from bothering me when I'm doing my homework," Itachi said, pushing Sasuke out of the room and into the hallway before closing the door in front of him with a small smile.

Sasuke let out a breath he didn't know he was holding. Unsurprisingly, Itachi was a frighteningly skilled shinobi, even in a different world. He would have to be careful around his brother. For that very moment, Sasuke was almost caught off-guard, a killer intent would have left him frozen in fear had he been Itachi's age.

The door opened again and Itachi stuck his head out from the doorway. "Nii-san, you'll need to go to the market today if you want dinner."

"Hm? Oh, okay," Sasuke answered without thinking. He wandered around the house a little bit before finding the exit of the compound, only to be called back by Itachi. "You forgot to bring a bag!"

He would need time to get used to this.

* * *

 **author notes:**

Thanks to awareofthewintersnow and da capo aria for beta-ing this chapter!

 **Lovingthefantasy**

Sorry we took so long to update. Hope you enjoyed the chapter! Constructive criticism is appreciated. Hopefully next chapter will be released sooner.

 **withabluepen**

Thank you to all the lovely readers that reviewed! If you are reading this, thank you for reading our fic. Reviews make us really happy! :D


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